Table Of Contentiv
Designus Maximus Unleashed!
flbout the luthor
Clive "Max" Maxfield si 6'1" tall, outrageously handsome, English and proud
of .ti In addition to being a hero, trend setter, and leader of fashion, he si widely
regarded as an expert in lla aspects of electronics (at least by his mother).
After receiving his B.Sc. in Control Engineering in 1980 from Sheffield
Polytechnic (now Sheffield Hallam University), England, Max began his career as
a designer of central processing units for mainframe computers. oT cut a long
stow short, Max now finds himself a Member of the Technical Staff (MTS) at
Intergraph Computer Systems, Huntsville, Alabama, USA, where he gets to play
with their high-performance 3D graphics workstations.
In his spare time (Ha), Max si a contributing editor to Electronic Design
News (EDN) magazine and a member of the advisory board to the Computer
History Association of California (CHAC). In addition to numerous technical
articles and papers appearing in magazines and at conferences around the world,
Max si also the author of the outstandingly successful Bebop to the Boolean
Boogie (An Unconventional Guide to Electronics), and the co-author of Bebop
BYTES Back (An Unconventional Guide to Computers).
On the off-chance that you're still not impressed, Max was once referred to as
an "industry notable" and a "semiconductor design expert" by someone famous
who wasn't prompted, coerced, or remunerated in any way!
V
Introduction
cknowledgment$
Just before we leap into the fray, I would like to take a few moments to thank my
staunch friend and good companion Alvin for his help, support, and
encouragement in this project, and I'd like to thank Alvin's wife Sue for letting him
come round to play at my house, l'd also like to thank Sue for her many
kindnesses (including, but not limited to, punishing her kids by making them weed
my garden whilst I sat chained to the computer). Thanks also go to my ex-wife
Steph for the long hours she spent proof-reading the final manuscript (any
remaining errors are mine own).
While a large part of this book si devoted to my musings on miscellaneous topics,
a key element si the accompanying CD-ROM, whose contents I hope you'll enjoy
experimenting with for years to come. So my grateful appreciation goes to
Maxfield & Montrose Interactive Inc., Madison, AL, USA (http://ro.com/maxmon)
for letting me present a demo copy of the Beboputer lautriV Computer, Alon
TM
,rifK ,AC USA, for allowing me to showcase his BOOL Logic Synthesizer; George
slliM of Softronics Inc., Northboto, ,AM USA (www.softronix.com) for allowing me
to feature his MMLogic MultiMedia Logic Design System; and Dave Gillooly of
IMP, Inc., San Jose, ,AC USA (www.impweb.com) for providing the material on
Analog Magic and related datasheets.
Many of the topics presented in this book have previously appeared in a
condensed and edited form as magazine articles, so l'd like to thank the following
magazines for allowing me to reprint these articles in their original form: cinortcelE
ngiseD News )NDE( magazine (www.ednmag.com), cinortcelE Design )DE(
magazine (www.penton.com/ed), and cinortcelE Design & Technology Network
)NTDE( magazine (www.edtn.com). Last but certainly not least, my thanks to
HighText Publications, Solana Beach, CA (www.hightext-publications.com) and to
Doone Publications, Madison, AL (www.doone.com) for kindly permitting me to
abstract and expand on certain topics from my earlier works.
viii
sungiseD Maximus Unleashed!
The EDN Series for Design Engineers
A. Kularatna Power Electronics Design Handbook: Low-Power Components and Applications
EDN Design Ideas (CD-ROM)
C. Sehroeder Printed Circuit Board Design Using AutoCAD
J. Lenk Simplified Design of Voltage-Frequency Converters
J. Lenk Simplified Design of Data Converters
F. Imdad-Haque Inside PC Card: CardBus and PCMCIA Design
C. Schroeder Inside OrCAD
J. Lenk Simplified Design of lC Amplifiers
J. Lenk Simplified Design of Micropower and Battery Circuits
J. Williams ehT Art and Science of Analog Circuit Design
J. Lenk Simplified Design of Switching Power Supplies
V. Lakshminarayanan Electronic Circuit Design Ideas
J. Lenk Simplified Design of Linear Power Supplies
M. Brown Power Supply Cookbook
B. Travis and I Hickman EDN Designer's Companion
J. Dostal Operational Amplifiers, Second Edition
T. Williams Circuit Designer's Companion
R. Marston Electronic Circuits Pocket Book: Passive and Discrete Circuits (Vol. )2
N. Dye and H. Granberg Radio Frequency Transistors: Principles and Practical Applications
Gates Energy Products Rechargeable Batteries: Applications Handbook
T. Williams EMC for Product Designers
J. Williams Analog Circuit Design: Art, Science, and Personalities
R. Pease Troubleshooting Analog Circuits
I. Hickman Electronic Circuits, Systems and Standards
R. Marston Electronic Circuits Pocket Book: Linear ICs (Vol. )1
R. Marston Integrated Circuit and Waveform Generator Handbook
I. Sinclair Passive Components: A User's Guide
Chapter :1
Who was that Masked
Man?
"And now my friends,
the show that never ends,
In this chapter you will discover:
.It.'s ................a ............F.u.nn.y. ...............................Ol.d. ....................W.o.rl.d. ............................. 4
It all Seemed Rather Pointless .....................................R.e.a.ll.y. ............................. 4
Beware the Jaberwock ..............................................m.y.. .................So.n .................... 5
International Computers: Shifters/Rotators ................................................... 6
Cirrus Designs: Test and .....................S.i.m.u.l.a.t.i.o.n. ............................................... 8
Intergraph Corporation' EDA and Back to Computers ..... 10
Articles, Conferences, .................a.n.d.. ......................B.o.ok.s. .............................. 11
...................................................S.o ................H.e.r.e .........................W.e. ...................A.r.e. .................. 14
4
sungiseD sumixaM !dehsaelnU
~t's a 3unng Old World
It really is a funny old world when you come to think about .ti Deep in the mists
of time when I was but a junior engineer, I occasionally thought that it would be
really cool to write technical articles and have them published in electronics
magazines. Only two things stood in my way:
a) I didn't know anything worth writing about.
b) Magazines weren't interested in me because I hadn't written anything
before.
Over the years l've come to realize that point (a) doesn't necessarily hold you
back as much as one might think, but point (b) is certainly something of a
show-stopper. As time passed I began to have the odd article published (and
some of them were really odd), until one day it appeared as though l'd crossed
some undocumented article-producing threshold known only to magazine
editors. Instead of being obliged to grovel with editors to have an article
published, I suddenly found myself having to beat them off with a stick. Now they
call me pleading for an article on "xyz," and happily ignore any protestations on
my part that I know nothing whatsoever about the subject in hand. Why should
this be? I don't know. That's just the way it .si
~t all Seemed I~ather Pointless i~eallg
When I started the English equivalent of High School at the tender age of 11
(Abbydale Grange Grammar School, Millhouses, Sheffield, England, on the
off-chance anyone is interested) I wasn't very good at English football (what the
Americans would call soccer). In addition to my seeming to have two left feet, no
one ever bothered to explain the rules to me. So whenever I actually gained
comrfland of the ball, the referee would shout something like "You're offside you
dingbat," and then they took the ball away from me again. It all seemed rather
pointless really.
On the bright side, one of my friends (who also didn't like football) was really
rather clever. Even for a precocious 11-year old, Carl Clements, l~I for that was his
name, knew an awful lot about electronics So while our compatriots were making
life miserable for the old pig's bladder, Carl would be explaining how to make an
audio amplifier using just one transistor (not a high-fidelity unit you understand),
describing the role of the bias voltage and drawing circuit diagrams in the play-
ground dust.
,lraCI long time on see. fI uoy happen to read ,siht drop em na email ta .moc.loa@bbpobeb
5
retpahC yI lsuoicirpaC gninnuC erawtfoS
The years rolled by and we moved on to more esoteric topics such as
bio-feedback. By the age of 14 we were huddled in our corner of the playground
designing brainwave amplifiers that could filter out alpha waves, amplify them,
and feed them back into headphones as pink-noise. 121 Sad to relate, these devices
never actually worked. The theory was sound, but we didn't have any test
equipment (in fact we didn't have much more than a soldering iron between us)
and we didn't have any training in testing circuits and resolving faults. Still later
we migrated into simple digital logic and then progressed to creating rudimentary
robots that rolled around the house and plugged themselves into power outlets
(on occasion they even managed to do this without vaporizing every fuse in the
house).
Looking back I guess all of this might seem pretty weird. fI I were to observe two
11-year olds of today sketching circuit diagrams in the playground while their
friends played games, l'd probably pause to ponder what cruel quirk of fate had
dealt them such a pathetic existence. But we actually had a great deal of "fun in
the sun," and it all seemed perfectly normal at the time.
~eware the ~aberwock my Son
In my last year at High School I was summoned into the august presence of the
Careers Officer, who loomed over the top of his desk and spake unto me thusly:
"Do you have the faintest clue what you want to be when you grow up you
sniveling little toad?" (Truth to tell, this master of the polyester fashion statement
didn't actually voice the words "you sniveling little toad," but it was certainly
implied in his sneer and his demeanor.)I31 When I replied: "I'm going to be an
electronics engineer," he responded with the following carefully considered gems
of advice, which I still treasure to this day: "Good .... you can go now .... send in
the next one on your way out."
And so it was that I meandered my way into the electronics course at Sheffield
Polytechnic (Now Sheffield Hallam University). I hated .ti We seemed to spend an
inordinate amount of time calculating the angular momentum of electrons and
listening to lecturers spout forth on similar apparently meaningless drivel. Not that
I have anything against electrons having angular momentum you understand, or
even that I particularly dislike calculating what it is. But once you've calculated
one electron's angular momentum you've done the lot as far as l'm concerned,
so this sort of thing became somewhat tiresome after the third week.
kniP"2 Noise" si sort fo like "White Noise," but it's a tib more lufroloc (pun intended). roF example,
the sound fo gnillaf rain might be equated to white noise, while the "churl ... churl ... chuff' fo an
dlo fashioned steam train would be a form fo pink .esion
enO3 gets to be more charitable over the years .... perhaps sih surly noitisopsid saw caused by sih
underwear riding up or some ralimis such happenstance.
6
sungiseD sumixaM !dehsaelnU
Knowing that there are a lot of electrons in the universe, 141 and with a growing
certainty that I would be required to calculate the angular momentum for each
and every one of them, I began to desperately search for a way out. After a little
rooting around I was amazed to discover that the "Electrical & Electronics"
course was one of the last places you wanted to be fi you actually wanted to
build electronic devices and (dare we say )ti have a bit of fun during the process.
So after my first year I transferred to a 4-year degree course in Control
Engineering, which turned out to be just what I'd wanted to do all along.
The Control Engineering course was based on a core of mathematics and control
theory, with surrounding subjects in electronics, mechanics, and hydraulics and
fluids. The entire course was geared up to building things and controlling them,
from factory systems to robots to fly-by-wire aircraft. Also, along the way we were
introduced to computers. Of course, in those days we wrote programs in the
FORTRAN language (ugggg, arrggghhh), entered them on punched cards,
walked through wind, rain, and sleet to the computer building, waited a week to
get the results (which were invariably along the lines of "Syntax error on line 2,
missing comma."), and then started the whole process again. In fact when you
finally got a program to work, you usually couldn't remember what had
prompted you to write it in the first place!
~nternational eomputer$: Shiftersll~otators
After graduating with a B.Sc. in Control Engineering in the Summer of 1980, my
first position ("Look Morn, a real job!") was with International Computers
Limited (ICL) in Manchester, England. At that time ICL made honking big
mainframe computers (they probably still do as far as I know), and I was hired as
a member of one of their Central Processing Unit (CPU) design teams.
It didn't take me long to discover that little of what l'd studied at college had
much bearing on my new job. lsI I also quickly realized that subjects which had
appeared easy in the classroom (when the lecturer was doing the bulk of the
work) were somewhat trickier when you had to do them in earnest. Fortunately,
ICL had a really good policy whereby junior woodchucks like myself were
partnered with more experienced team leaders. I was lucky in this regard to be
assigned to one Dave Potts, who taught me far more than l'm sure he ever
realized. Working under Dave was somewhat frustrating, however, in that he
would never answer even the simplest question directly; for example:
sselnU4 there's only eno nortcele that moves around ylloj ylkciuq and pops ni dna tuo fo ecnetsixe
rehtih dna ,rehtiht sa saw once detalutsop yb eht yradnegel tsicisyhp drahciR .namnyeF
oT5 be ,riaf almost gnihtyreve I learned ta egelloc sah yltneuqesbus come ni handy ta one emit ro
.rehtona
7
Chapter I Capriciously Cunning Software
Max: Hey Dave, what time is it?
Dave: Where is the sun in the sky, which way is the wind blowing, what side
of the tree does the moss grow, how ......
To cut a long story short, Dave's policy was to lead you through a series of
questions, thereby guiding you to discover the answers to life, the universe, and
everything for yourself. In many ways this proved to be a superb learning
experience (but you quickly learned not to ask Dave for the time).
My first task at ICL was to design a 128-bit barrel shifter and rotator; that is, a
unit that could shift or rotate the contents of a 128-bit bus by any amount from
1 to 128 bits in a single clock cycle. Dave informed me that the project called for
this unit to be implemented using eight Application-Specific Integrated Circuits
(ASICs), each of which would handle a 16-bit chunk of the data bus.
Furthermore, all of the ASICs were to be functionally identical in order to keep
the project within budget.
Initially my task didn't appear to be particularly strenuous. The only tricky details
involved inserting the appropriate values into the most- and least-significant bits
for right and left shifts, respectively (and handling logical versus arithmetic shifts
of course). The solution was to employ two of the pins on each ASIC to act as a
device ID; that ,si these two pins could be presented with one of four binary
patterns (OO, ,1O 10, and ,)11 thereby instructing the device as to its position in the
chain. For example, the six devices forming the middle of the chain could have
these two pins driven to ,OO the device on the left-hand end of the chain could
have its pins driven to ,1O and the device on the right could be driven to .01
When l'd completed this part of the exercise, Dave deigned to inform me that
he'd neglected one slight detail, which was that in addition to shifting all 128 bits,
the shifter/rotator also had to be capable of shifting only the least-significant 64
bits or the least-significant 32 bits. OK, my task had just become a tad trickier,
but it still wasn't all that bad and a few days later I returned with my latest
offering. "Ah, Fla!" said Dave, "now we're getting there, but ni addition to binary
shifts, this device also has to be able to handle Binary-Coded Decimal (BCD)
data!" And so it went. Every time I finished a problem another feature would be
added to my portion of the project. In reality, of course, the specification already
contained all of these details, but fi l'd been presented with the full requirements
on my first day, my brains would have leaked out of my ears and I would have
been reduced to a gibbering wreak.
These days engineers have access to some very sophisticated tools, such as
schematic capture (Chapter 5), logic simulation (Chapter 6), timing analysis
(Chapter 7), and so forth. But in those days of yore, the best one could hope for
8
sungiseD Maximus Unleashed!
was a good data book, a sharp pencil, a lot of paper, and a pocket calculator
fi( you were lucky). The project specifications called for a certain clock frequency,
from which one could derive the maximum permitted delays across my devices.
My next task was to calculate the input-to-output delays by hand, then juggle the
logic gates inside the device until l'd achieved my target.
Last but not least, each device could only accommodate a certain number of
logic gates and registers, and I was dreadfully over budget. Unfortunately, we
didn't have access to anything like today's logic synthesis technology
(Chapters 3 & 5), but we had something far better! One of the members of our
team was a 30-year old Chinese engineer, whose forte was logic minimization
and optimization, l'm sad to say that I no longer remember the lad's name, but
this guy was incredible ~ a grand master of logic ~ and I'd put him up against
today's automatic tools without any hesitation at all.
eirrus Designs: ~est and Simulation
My mother was delighted when I was accepted by ICL, because she could see a
steady progression through the corporate hierarchy, yay even unto the highest
pinnacles of power (my mother had remarkably good eyesight in those days). So
you can only imagine her surprise and delight when, after just one year, I
departed ICL to join a start-up company called Cirrus Designs. Upon discovering
that my new employer had only been incorporated for a few days, my mother
became full of doom and despondency (and she wasn't one to suffer quietly or
alone ~ sorry Dad). Strange to relate, she now claims that this was the best
move she ever told me to make, and when I question her recollection of events
she stridently informs me that: "A mother remembers these things!" and who
amongst us can argue with that. ~6~
I was the sixth person to join Cirrus Designs, and the other five told me that I was
a lucky swine because I'd joined the day after the desks and chairs had arrived.
Our sole computer facilities comprised a PDP 11-23, with two terminals and
keyboards between us. The hard disk only had a single directory that we lla had
to share, 171 and each of us was allocated only 2000 blocks of disk space (where
each block held 1024 characters). It seemed like a lot at the time!
When Cirrus Designs commenced operations, we used to have a weekly "state of
the company" meeting to see how well we were doing. Unfortunately, I think the
founders had assumed that when you did some work for somebody they would
pay you for it immediately, so it came as something of a shock to discover that it
yM6 mother's memory si os acute that ehs nac remember sgniht that haven't even happened !tey
ehT7 last retcarahc fo a elif name detacidni sti .renwo yM rettel saw ,"M" os yna elif dellac xxx.Mxxx
saw one fo .enim
9
Chapter I Capriciously Cunning Software
..... ._ . . . . . . . . . . . . . . . . - ....................... . . . .......................................................................................................... - ........... --. .............
was common to wait for 90 days before you smelled any cash. Thus, week by
week the company funds headed ever South, until at one point we were asked to
provide our own pencils and paper. Then suddenly the graph flattened out ...... a
little later it even began to rise ...... and ...... by golly we'd made !ti
l've been very fortunate in my career to have been exposed to many aspects of
electronics, but perhaps the most fortuitous was learning how to write test
programs. The main service provided by Cirrus Designs in the early years (circa
1981 to 1984) was to write functional test programs for circuit boards designed
by other companies. These programs were developed using GenRad's 2225
testers, into which one plugged the board to be tested, ~St A test program consisted
of driving a pattern of logic sO and logic ls into the board's inputs, waiting for
their effect to propagate through the board, and checking that the corresponding
pattern of logic 0s and logic l s on the board's outputs matched an expected
response. 191 Each pattern applied to the inputs was called a test vector, and a test
program could consist of thousands (or tens of thousands) of such vectors.
My personal view is that l've never received better training than learning to write
these test programs. To understand why this should be so, you have to realize
that all one was provided with was a "good" circuit board (which often wasn't),
and a set of "good" schematics (which often weren't). It wasn't unknown (he said
with a wry grin) for the schematics to actually correspond to an earlier or later
version of the board, which made life interesting to say the least. First you had to
look at the schematics and try to decide exactly what it was that the board was
intended to do, then you had to write a test program. Next you ran the test
program while applying a fault to the board (such as shorting a device's output
pin to ground) in order to ensure that the program could detect and resolve the
fault, and you repeated this for every possible fault that could occur on the board.
So in addition to reverse-engineering someone else's logic (which is an
educational experience in itself), you also discovered portions of the design that
were effectively untestable, and you did this to boards designed for myriad
applications by different engineers in diverse companies using widely different
design styles. As I said, this was the best training in digital logic one could hope to
receive.
After a few years of test programming, I wandered into my boss's office to find
him pondering a request to write some digital simulation models. The problem
was that none of us had actually seen a digital logic simulator "in the flesh," but
the remuneration (for the company) was particularly attractive. I remarked that
surriC8 sngiseD yltneuqesbus became a yllohw owned yraidisbus fo GenRad, Concord, ,AM .ASU
f19 eht board contained retsiger stnemele or memory ,secived then a pattern appearing no eht
board's outputs didn't ylirassecen correspond to eht current pattern on sti ,stupni but saw instead a
noitcnuf fo eno ro more gnidecerp .snrettap
